023687.SO.0128.beauty.5.AS Studio City,CA. Use of food in beauty treatments food in spa services, such as facials and other skin treatments. Esthetician, Traci Pokelsek at Spoiled A Day Spa in Studio City puts cucumber slices over the eyes to calm, soothe, and filter light for the eyes while applying a facial in which fresh mushed bananas and warm honey are applied to the face of customer Alyson Fox. (Photo by Al Seib/Los Angeles Times via Getty Images)

Your favourite exfoliating face wash or toothpaste may be up for a recipe change as Australia's supermarkets make moves to phase out plastic-derived microbeads.

On Thursday night, Environment Minister Greg Hunt said major supermarkets Coles and Woolworths would no longer create products with the tiny plastic balls.

But what are microbeads, how do they compare to microplastics and what effect are they having on our oceans?

"We want to work with industry to do this. Already Coles and Woolworths have responded and committed to banning microbeads from their shelves by the end of 2017.

"But we want to see a full national phase out."

As it stands, it is not against any law or code to produce products with microbeads and while Coles no longer produces any of its own products with microbeads, a Woolworths spokesman told The Huffington Post Australia they were working to replace the ingredient.

"We have been working to phase out microbeads in our own brand skin and body wash products and at present we have one remaining product -- it is due to be phased out in the coming months," the Woolworths spokesman said.

Neither supermarket has committed to a ban on selling products with microbeads but both noted they would work with suppliers in regards to the government's call for a voluntary phase out.

What are microbeads?

They're tiny pieces of plastic added to face wash, toothpaste, abrasive cleaners and other products. They're too small to be caught in water filtration systems and can be swallowed without noticing.

You can find them on a list of ingredients labelled polyethylene, HDPE, high-density polyethylene or PEHD.

What are microplastics?

Microplastics are any piece of plastic smaller than 5mm, including microbeads. Some are visible to the naked eye and some are not.

What are the main causes of microplastics?

Interestingly, not microbeads.

University of NSW professor of ecotoxicology Emma Johnston headed up research undertaken at Sydney Institute of Marine Science looking for microplastic in sediment and fish around Sydney Harbour.

She said the big culprit in both instances was most probably derived from synthetic clothing.

"In Sydney Harbour, microbeads are not the major contaminant as far as microplastics are concerned. In sediment and fish samples we made, by far the dominant contaminant was microplastic in fibre form," Johnston said.

“These fibres come from things like nylon and polyester which points to clothing. Then other fibre sources are some fishing gear, sandbags, nappies, even flushable wipes."

She said the second most common source of microplastic was as a fragment, broken down from bigger plastic pieces like PET bottles.

Microbeads were last, however she cautioned Sydney Harbour was just one site.

"Maybe microbeads are more buoyant and they float out of the Harbour."

How do we know microplastics harm marine life?

Johnston said there were two ways: by being eaten, and by absorbing toxins attached to them. She said they'd seen everything from very small worms right through to mullets and bream that had eaten microplastics, with different effects.

“Direct metabolic disruption is likely in very small organisms like plankton,” Johnston said.

“They ingest microplastics and it accumulates in the gut to the point where it blocks the passage of food.

"One issue with bigger fish that its been shown microplastics can transfer from the gut into the blood stream and muscles which is a big concern, because the body doesn’t like foreign objects, it causes fibrosis.

"Though it has only been shown in three studies so we need to know lot more about it."

What's more concerning is the fact that microplastics are often coated with toxins.

“Microplastics are like sponges – they will suck up all other hydrophobic contaminants around them that bind to surface," Johnston said.

“When fish feed on contaminated microplastics, the toxins de-absorb in the gut and are taken up by the fish into their tissues.

“We calculated an average mullet encountered 10,000 microplastic particles per year and that means they’re potentially absorbing a lot of chemicals and other contaminants.”